512 



SNODGRASS AND HELLER 



Rivillagigido Archipelago, Cocos Island and Galapagos Archipelago. 

 We saw one individual of this species at Chatham Bay, Cocos 

 Island, in July. 



SULA CYANOPS (Sundevall). 



Dysporns cyattops Sundevall, Phys. Tidskr., Pt. v, p. 218, 1837. 



Sula cyanops Ogilvie-Grant, Cat. Birds Brit. Mus., xxvi, p. 430, 1898. 



Range. — Intertropical. In the Eastern Pacific : Clipperton Island 

 and the Rivillagigido Archipelago. 



Adult Male and Female. — Pure white except primaries, seconda- 

 ries, tertiaries, greater wing coverts and rectrices, which are sooty- 

 brown. Tail feathers white at base ; inner webs of secondaries whitish 

 toward base ; basal half of tertiaries white ; shafts of wing quills 

 black, of median tail feathers yellowish-white. Bill plain horn-yel- 

 low. Feet, in dried skin, dark brown. 



This bird is identical in plumage with Sula variegata of the coast 

 of South America and the Galapagos Islands, differing from it in hav- 

 ing no red color on the bill, which is yellow. There are also some 

 differences in proportions. 



The collection contains four adult males, all taken at Clipperton in 

 November. 



MEASUREMENTS, IN MILLIMETERS, OF Sulu CyUtlOpS. 



On Clipperton this bird was found breeding in immense numbers in 

 November. The nests consisted of slight depressions scraped in the 

 coral sand and contained one or two eggs each. The nesting had just 

 begun for no incubated eggs or young birds were seen. A set generally 

 consisted of two eggs, but w^e were assured by people living on the 

 island that only one young bird of each pair is reared, the other being 

 left by its parents to starve on account of the extreme voracity of the 

 young. The young, we were told also, are taught to swim and dive in 

 the quiet water of the lagoon before venturing out on the open ocean. 



The most common note uttered by the adults was a loud quack. 

 Occasionally a sharp whistle was heard, but no special significance to 

 this sound was observed. 



